Bad luck if you're a fast-paced Tumblr fiend running anything less than Android 2.1 on your Android. Their first official Android app has no place on your phone.
It was released to the Market over the weekend, and offers almost the same level of use that the iPhone version does. Namely, you can post text, photos, links, video and audio to a Tumblr feed, as well as read subscribed Tumblrs within the app. At the moment, it sounds as though Tumblr hasn't included the same Twitter support that's included in the iPhone version.